128 DAKYNS: GLACIAL BEDS AT BRIDLINGTON. 
blue rocks, like these boulder clays, as a means of identify- 
ing beds far apart, red is about the most delusive : as alJ 
blue rocks are apt to turn red by chemical action, save when 
under some considerable cover ; and thus the upper parts of 
blue rocks, where they come to the surface, are more likely 
than not to assume a red hue. I think that to some 
observers the warning is needed that the Latin poet gave 
to the handsome lad — " nimium ne crede colori." 
Note. — It is as well to state that the Purple Boulder 
Clay of Holderness is in many places distinctly stratified. 
ON THE ORIGIN AND FORMATION OF THE WOLD DALES. 
BY REV. E. MAULE COLE, M.A., ETC. 
In a paper on the Red Chalk, which I had the honour to 
address to your Society last year, I said, with reference to 
the surface configuration of the Wolds, that the rim or 
highest portion of the basin of the chalk area was now 
thinnest "owing to subaerial denudation." 
These latter words have been objected to by a friendly 
critic, who says that I ought to have written "owing to 
submarine denudation." 
This criticism opens at once the floodgates of controversy. 
Different men, equally distinguished as geologists, hold 
different opinions on the subject of denudation. 
Let me first explain my meaning in the quotation alluded 
to. All that I meant to assert was, that after the final 
emergence of the chalk area of the East Riding above the 
sea level, that portion of it which constitutes the high Wolds 
was exposed to subaerial denudation, and therefore reduced 
in thickness and made so far thinner in comparison with the 
other portion, which is protected from atmospheric influences 
by the Boulder Clay of Holderness (see Appendix A). I did 
not mean that in the process of elevation no other causes 
